Motor fuel production



y 8, 1941- e. ARMlSi'EAD, JR 2,248,842

MOTOR FUELPRODUCTION Filed Oct. 23, 1937 FlG.2.

64 INVENTOR GEO/F65 ARM/876790 J7? BY am ATTORNEY Patented July 8, 1941 UNITED STATES PATENT OFFICE MOTOR FUEL PRODUCTION George Armistead, Jr., Scarsdale, N. Y., assignor to Process Management Company, Inc., New

York, N. Y., a-corporation of Delaware Application October 23, 1937, Serial No. 170,603

3 Claims. (Ol, 196-9) This invention relates to the treatment of hydrocarbons for the production therefrom of lower boiling hydrocarbons. More particularly, the invention relates to the treatment of a plurality of hydrocarbon fluids of differing boiling ranges for the production of motor fuel of high anti-knock value. More particularly, the invention relates to the treatment of a crude oil for the production of motor fuel therefrom under conditions of.

maximum efiiciency.

It is an object of the invention to provide a method of treating a plurality of hydrocarbon fluids including normally gaseous hydrocarbons wherein the treatments of the various fluids are correlated in a combined operation to effect maximum production of motor fuel of high antiknock value under conditions of highest emciencyand with a minimum requirement in apparatus.

It is a further object of the invention to provide a method of treating a heavy oil wherein lower-boiling intermediate oils and convertible normally gaseous hydrocarbons produced in the treatment of the heavy oil are returned to the process for treatment with the heavy oilwhereby the heavy oil, the lower-boiling intermediate oil and the normally gaseous hydrocarbons are subjected to conditions suitable to effect conversion of each to motor fuel, or to intermediate products from which motor fuel may be produced, under conditions of maximum efficiency.

It is a further object of the invention to provide a method of treating crude .oil wherein said crude oil is divided into a plurality of fractions and said fractions and intermediate products produced therefrom are treated undertonditions of maximum eiiiciency to effect conversion thereof to motor fuel of high anti-knock value.

It is a further object of the invention to provide an improved cycle of operation having such other advantages which may be found to obtain, as set forth in the following description.

The invention contemplates the treatment of a hydrocarbon oil, preferably a light or intermediate clean hydrocarbon oil, under elevated conditions of temperature and pressure, which may be sufficient to effect conversion thereof to motor fuel of high anti-knock value. A heavy hydrocarbon oil, such as a reduced crude or a heavy gas oil, is merged with the heated oil. Convertible normally gaseous hydrocarbons, such as Ca and C4 hydrocarbons are also admixed with the first-mentioned hydrocarbon oil prior to the application of heat thereto and/ or later. The merged products are thereafter subjected to cracking conditions of temperature and pressure to effect cracking of the heavy hydrocarbon oil to lighter products which may include motor fuel, conversion of the normally gaseous hydrocarbons to normally liquid hydrocarbons; and conversion of the light or intermediate hydrocarbon oil 'as desired. The joint treatment of the normally gaseous hydrocarbons and. the heavy hydrocarbon oil in the presence of the light or'intermedialte hydrocarbon oil and any conversion products thereof promotes reaction between the normally gaseous hydrocarbons'and normally gas--- eous and normally liquid conversion products of the hydrocarbon oils with the resultthat the over-all production of gasoline constituents is increased and the production of gases is minimized. The prolonged digestion of the heavier residual constituents of the heavy oil under the outlined conditions lowers their viscosity as well as aids the production of intermediate boiling range stocks which can subsequently be cooled to motor fuels or withdrawn from the system as desired.

The relatively heavy hydrocarbon oilconveni-l ently may be a reduced crude which constitutes the fresh feed to the system, and the light .or intermediate hydrocarbon oil and the convertible normally gaseous hydrocarbons 'may be cycle. stocks. The operation conveniently maybe carried out in a single heating zone such as] a. pipe coil arranged in a heating furnace whereby the various parts are given the desiredapplications of heat although this may be supplemented by-a reaction chamber of appropriate size. if desired.

Preferably the light .or intermediate hydrocarbon oil, which may be partially or entirely a cycle stock from the system, is introduced into the coil at the inlet together with normally gaseous hydrocarbons as desired and passed through a suiiicient portion of the coil under conditions of temperature, pressure and time suitable to' effectsubstantial conversion of the oil prior to the admixture therewith of the heavier oil. and any further normally gaseous hydrocarbons. These are then introduced into the coil atone or more points after being preheated if desired and. are passed through the remainder of the coil with the unconverted light or intermediate hydrocarbon oil and conversion products thereof under conditions of temperature and pressure sufficient to effect the desired conversion of the heavy oil and normally gaseous hydrocarbons and further conversion of the light or' intermediate hydrocarbon oil if desired. 1

The conversion products are then separated into vapors and liquid residue, and the vapors are fractionated to obtain therefrom a suitable condensate above the motor-fuel boiling range, a motor-fuel condensate, and a normally gaseous distillate which may be further fractionated to separate therefrom a condensate consisting essentially of the most easily convertible hydrocarbons such as the C3 and Cr hydrocarbons which may be recycled as described above.

The invention is particularly applicable to the treatment of a plurality of hydrocarbon fluids and intermediate products therefrom, such as are obtained by the distillation of crude oil, to effect conversion thereof into motor fuel of high antiknock value. For example, crude oil may be fractionated to separate therefrom a gaseous product,

a light naphtha condensate, a heavy naphtha condensate, a virgin gas-oil condensateandya heavy oil which may be a condensate or reduced crude. The gaseous distillate may be subjected to fur ther fractionation to separate therefrom the most easily convertible hydrocarbons such as the C3 and C hydrocarbons.

The heavy naphtha condensate and the virgin gas-oil condensate may be separately treated under elevated conditions of temperature and pressure to effect conversion thereof to motor fuel of high anti-knock value by reforming the heavy naphtha and by severely cracking the virgin gas oil. Cycle condensate produced in the system may beseparately subjected to elevated conditions of temperature and pressure to effect cracking thereof to motor fuel.- I

The heavy oil or'reduced crude obtained from the distillation of the crude oil and normally gaseous hydrocarbons obtained as described above, together if desired with similar hydrocarbons recovered from the system, are then merged with the hot conversion products of one or more of the separate conversion treatments, and. the merged products are thereafter subjected to cracking conditions of temperature and pressure to effect cracking of the reducedcrude and conversion of the normally gaseous hydrocarbons to hydrocarbons within the motor-fuel boiling range or to heavier hydrocarbons and further conversion of the light ,or intermediate hydrocarbon oil as desired. Products of the cracks ing of the merged materials and, other conversion products from the system are fractionated to pro.- vide a cycle condensate, a motor fuel condensate, and, a normally gaseous distillate which, may be recycled. to the system preferably after removal of C2 hydrocarbonsv and lighter gases.

The accompanying drawing illustratesspecific embodiments of the methods generally described above. Fig. 1 is a diagrammatic view in. elevation of apparatus suitable for carrying out the invention in a simple application thereof.

Fig. 2 is a diagrammatic View in :elevationIof apparatus suitable forthe application of the invention to the treatment of a plurality of hydrocarbon fluids of varying boiling ranges such as are produced'by the distillation of crude oil- The invention will be described in detail with refer: ence to the drawing, but it is to beunderstood that the invention is not limited thereby but is capable of other embodiments which may. be beyond the physical limitations of the apparatus indicated. 1

Inthe drawing, referring to Fig, l, a light or intermediate hydrocarbon oil, which may be a cycle condensate produced in the system as described below, or which may include a suitable clean hydrocarbon oil introduced into the system through means not shown, is passed through line I by means of pump 2 and introduced into the coil of heater 3 at the inlet thereof. The oil may be preheated prior to introduction into heater 3 if desired by means not shown such as direct heating or by heat exchange with hot products from other parts of the system. In heater 3 the cycle condensate is passed through a suilicient length of the coil of heater 3 under elevated conditions of temperature and pressure and at a velocity whereby substantial conversion is effected prior to admixture with other fluids as described below. For example, a clean hydrocarbon oil having an end point of 650 to 750 F. may be heatedto a temperature of 900 to 1050 F, at a pressure. of 400 to 600 pounds per square inch for a time sufiicient to effect maximum conversion without excessive deposition of coke.

A heavy hydrocarbon oil which may be a reduced crude is introduced as fresh feed to the system through line 4 by means of pump 5'. 'Line 4 connects. with the coil of heater'3 at one or more intermediate points thereof whereby the said reduced crude is merged with the lighter oil, which has been subjected to substantial cracking at one or more points as desired. Line 4 is provided with-a plurality of branches 4a, 4b and 40 which connect with the coil of heater 3 at separate points. If desired, the reduced crude may be preheated by suitable means not shown prior to introduction into the coil of heater 3.

Simultaneously, there is introduced into the coil, at the same points'of introduction as the reduced crude or at separate points, gases containing a substantial proportion of convertible normally gaseous hydrocarbons such as C3 and C4 hydrocarbons, preferably predominating in the latter. These gases. may be passed through line 5 which is provided withbranches 5c;v and 5b which connect with the coil of heater 3 at different points. normally gaseous hydrocarbons may coincide with those of the reduced crude or may be spaced apart. therefrom. It is desirable, however, that the gases be thoroughly admixed with the stream passing through the coil 'of heater 3 before substantial cracking of the reduced crude iseffected. Optionally all or a part of the gases maybe introduced into admixture with the stream of oil prior to heating the latter, for example, through line 5c'which connects lines I and 5. The nor mally gaseous hydrocarbons may consist wholly or in part of cycle stock or may include gases produced externally of the system and introduced by means not shown. Line 5 includes heat exchangers 6 and 1 whereby the normally gaseous hydrocarbons are preheated prior to introduction into the coil of heater 3, and other heating means not shown may be provided for further preheating, of thenormally gaseous hydrocarbons as desired.

The conversion products from heater 3 are withdrawn therefrom through line 8 provided with control valve 9 and are introduced into evaporator I 0 wherein separation ofv the vapors and liquid residue occurs. Evaporator I0 may be provided with suitable baffling in the upper portion thereof to effect separationof entrained matter from the vapors, if necessary, to permit passage overhead of vapors including a suitable clean cycle stock above the motor-fuel boiling range for heater 3. Fractionator It) may be operated at a pressure of 50 to 250 pounds per square inch. I

' The vapors separated in evaporator l0 are.

The points of introduction of the withdrawn therefrom through line I2 and introduced into fractionator I 4 after being cooled by passage through heat exchanger 6 in indirect contact with the normally gaseous charge to the coil of heater 3. Additional cooling means may be provided if desired for cooling the vapors prior to introduction into fractionator [4. In fractionator l4 conditions of temperature and pressure are maintained to effect condensation and separation of hydrocarbons above the motor-fuel boiling range, which condensate is withdrawn through line I for passage to the heater 3, as described above or withdrawn from the system for treatment elsewhere by means not shown. For example, fractionator [4 may be operated at a pressure of 50 to 250- pounds per square inch with a bottom temperature of 550 to 650 F. and a top temperature of 350 to 425 F.

C001ing coil I6 may be provided in the top of fractionator [4 to supply the reflux necessary to effect the desired fractionation.

The vapors uncondensed in fractionator 14 pass overhead through line I! and after being cooled by passage through heat exchanger I in indirect contact with the normally gaseous charge to heater 3 are further cooled and condensed in coil II and enter separator I 3 where a separation of liquid and gaseous products takes place. The gaseous products are introduced by means of compressor l through line 24 and liquid products are passed through pump, l5, line l8 and heat exchanger l8 to an introduction point near the top of a fractionator H]. In fractionator l9 conditions of temperature and pressure are maintained to effect condensation and separation of a substantially stabilized motor fuel which is withdrawn through line 20 provided with control valve 2| and passed through heat exchanger 18'. For example, fractionator l9 may be maintained at a pressure of 250 pounds per square inch with a top temperature of 120 F. and a bottom temperature of 300 F. Heating coil 22 and cooling coil 23 may be provided in the bottom and top, respectively, of fractionator I 9 to effect the desired fractionation.

The gases uncondensed in fractionator l9 are withdrawn therefrom through line 24' which connects with line 24 which in turn connects with a fractionator 25 whereby gases from separator l3 and fractionator l9 are introduced therein. In fractionator 25 conditions of temperature and pressure are maintained to effect condensation and separation of the normally gaseous hydrocarbons most suitable for conversion reactions, for example, the C3 and C4 hydrocarbons. If desired, a portion of the C1 and C2 hydrocarbonsmay be included in the condensate. Fractionator 25 may, for example, be maintained at a pressure of 300 pounds per square inch with a top temperature of 30 F. and a bottom temperature of 120 to 140 F. Heating means 21 may be provided in the bottom part of fractionator 25 to strip undesired gases from the condensate, and cooling means such as refrigerating coil 28 may be provided in the upper portion of fractionator 25 to maintain the desired fractionation. Uncondensed gases are withdrawn from the upper portion of fractionator 25 through line 29 provided with control valve 30.

The condensate is withdrawn from fractionator 25 through line 5 by means of pump 3| and introduced into the coil of heater 3 in the manner described above. However, condensate thus obtained may be withdrawn from the system for treatment elsewhere by means not shown or additional similar normally gaseous hydrocarbons may be introduced to the system by means not shown for treatment with the condensate withdrawn from fractionator 25.

Preferably, the gases introduced into the coil of heater 3 through line 5 consist essentially of the most easily convertible hydrocarbons such as C: and G4 hydrocarbons. However, they may include also lighter hydrocarbons and other gases from the system such as 02 hydrocarbons, methane and hydrogen. For example, all or a portion of the gases withdrawn from the fractionator l9 through line 24 may be diverted from line 24 through line 33 and introduced directly into line 5 for passage to heater 3. Valves 34, 35 and 36 in lines 5, 24 and 33, respectively, may be provided to permit the desired distribution of the gases through line 33 and fractionator 25.

Suitable gas and liquid 1 contact; means are provided in towers l4, l9 and 25 to eifect the condensation, evaporation, stripping and absorption incidental to fractionation.

Referring to Fig. 2,a crude 'oil or partially topped crude oil introduced to'the system through line 31 by means of pump 38 may be preheated in heater 39, for example, to a temperature of 500 to 700 F. at a pressure of atmospheric to pounds per square inch. The heated crude oil is then passed through line40 for introduction into crude flash tower 42 provided with trap-out trays 43 and 44 and cooling means 45 at the topthereof to effect fractionation of the crude oil as desired. Flash tower 42 is maintained at conditions of temperature and pressure to cause vaporization of a. substantial proportion of the crude oil and inclusion in the vapors of constituents suitable for drastic cracking treatment and lighter constituents and the production of. a reduced crude which collects in the bottom of tower 42. .The vapors are fractionated to efiect separation and recovery of a virgin gas-oil condensate which collects in trapout tray 44 and a heavy naphtha condensate which collects in trap-out tray 43. Light naphtha and lighter constituents pass overhead through'line 41 provided with'control valve 48. For example, tower 42 may be operated at a pressure of atmospheric to 100 pound-s per square inch with a top temperature 015250? to 350 F. and a bottom temperature of 550. to 750 F.

The heavy naphtha collected in trap-out tray 43 is withdrawn therefrom through line 49 by means of pump 50 and introduced into the coil of reforming heater 5! wherein it is subjected to elevated conditions of temperature and pressure to effect reformingof the heavy naphtha and conversion thereof to motor fuel of high antiknock value.

Similarly, virgin gas oil collected in trapout tray 44 is withdrawn therefrom through line 52 by means of pump 53 and introduced into the inlet of the coil of heater 54 wherein the gas oil is subjected to elevated conditions of temperature and pressure to effect substantial cracking thereof to lighter constituents including a substantial proportion of motor-fuel constituents of high anti-knock value. 7

Similarly, a cycle gas oil collected in the system asdescribed below may be passed through line 55 by means of pump 56 and introduced into the inlet of the coil of heater 5'! wherein it is subjected to elevated conditions of temperature and pressure to efiect cracking of the cycle stock to lower-boiling products including gasoline constituents of high anti-knock value: and with minimum deposition'of coke.

Reduced crude collected inv the bottom of tower 42 is withdrawn therefrom through line 58 by means of pump 59, and: all or a portion thereof may be introduced into the coil of heater 51 at one or more points intermediate the ends thereof, or all or a portion of the reduced crude in line 58 may be diverted therefrom through line 60 and introduced into the coil of heater at one or more points intermediate the ends thereof, or all or a portion of the reduced crude passing through line 58 may be diverted therefrom through line GI and introduced into the coil of heater 54 at one or more points intermediate the ends thereof. Valves 62, 63 and 64 are providedin lines 58, 60 and 6|, respectively, to effect any desired diversion or distribution of the reduced crude to one or more of the three heaters 5|, 54 and 51.

The introduction of the reduced crude into the coil of a heater, as described above, is arranged whereby the lighter oil introduced into the coil at the inlet thereof is first subjected to substantial conversion before admixture with the reduced crude. The reduced crude may be preheated prior to such introduction, and the proportion thereof introduced into the coil and the degree of heating of the-merged products thereafter is controlled to effect rather drastic cracking of the reduced crude with production of lighter products therefrom including gasoline constituents of high anti-knock value.

A stream of normally gaseous hydrocarbons which preferably predominates in the C3 and/or C4 hydrocarbons and which may be suitably produced. in the system as described below is passed through line 64. When reduced crude is being introduced into the coil of heater 51 through line 58 all or a portion of the normally gaseous hydrocarbons in line 64 are, diverted therefrom through line 65 which connects with the coil of heater 51 at one or more points whereby the normally gaseous hydrocarbons are intro- 1 7 duced into admixture with the light and heavy oil undergoing treatment therein. The introduction of the normally gaseous hydrocarbons into the coil, of heater 51 is arranged to provide admixture of the normally gaseous hydrocarbons and the oils undergoing cracking before and/or after the light oil has undergone substantial conversion but prior to. subjection of the heavy oil or reduced crude to drastic crackingconditions for any substantial period. The presence of the convertible normally gaseous hydrocarbons. in the merged products undergoing cracking treatment inthe coil of heater 51. tends to minimize the production and formation of coke due to the drastic cracking of the reduced crude and promotes reactions between the normally gaseous hydrocarbons and conversion products thereof with conversion products of the liquid hydrocarbons undergoing treatment with a resultant decrease in gas production and. increase in liquid products in the gasoline boiling range as well as crackable hydrocarbons of high boiling range which can be converted to gasoline by further thermal treatment.

Similarly, at least a portion of the normally gaseous hydrocarbons passing through line 64 may be diverted through line 66 and/or line 61 for introduction into the coil of heater 5| and/or the coil of heater 54, respectively, at one or more points thereof when. reduced crude is being introduced into the. coil of heater 5| through; line 60 and/or into the coil of heater 54 through line 6|, respectively. Valves 68, 69 and 10' are provided in lines 65, 66 and 61, respectively, to effect any desired diversion or distribution of the normally gaseous hydrocarbons from line 64. The normally gaseous hydrocarbons may be preheated as desired prior to introduction into the coils of heaters 5|, 54 and 51 by any suitable means as described below.

The temperature and pressure in the coils of heaters 5|, 54 and 51 are maintained to effect substantial conversion of the relatively light oil introduced into the coils at the inlets thereof prior to admixture with heavy oil or normally gaseous hydrocarbonsand to effect conversion of said heavy oil and saidnormally gaseous hydrocarbonsto gasoline constituents of high anti knockvalue together with additional conversion of the relatively light oila desired. For example, in heater 5| the heavy naphtha may be subjected to a temperature of 950 to 1050 F. at a pressure of 500 to 1000.pounds per square inch to effect reforming prior to admixture of reduced crude or normally gaseous, hydrocarbons therewith. After such admixture the merged products may be maintained at less drastic conditions, for example, at a temperatureof 850 to 950 F. and at the same or lower pressure. In heater 54 the virgin gas oil may be subjected in the first part of the coil to a temperature of 900 to 1100 F. at a pressure of 200 to 1000 pounds per square inch prior to introduction of the reduced crude and normally gaseous hydrocarbons. After such admixture the merged products may be subjected to a temperature of 850 to 950 F. at the same or lower pressure. In heater 51 cycle stock introduced through line 55 may be subjected to a temperature of 900 to 1075 F. at a pressure of 200 to 1000 pound per square inch, and after any admixture therewith of reduced crude and normally gaseous hydrocarbons the merged products may be subjected to a temperature of 850 to 950 F. at the same or lower pressure.

The cracked products from heaters 5!, 54- and 51 are withdrawn therefrom through lines 1|, 12 and 13, respectively, which connect with evaporator 14. Lines 15, 16 and 11 connect lines 1|, 12 and 13, respectively, with a separate evaporator 18. Valves 19, 80, 8|, 82, 83 and 84 are provided in lines 1|, 15, 12, 16, 13 and 11, respectively, to eifect any desired reduction in pressure of the cracked products and, the desired distribution thereof to evaporators 14 and 18.

The distribution of cracked products from heaters 5|, 54 and 51 is governed by the distribution of reduced crude and normally gaseous hydrocarbons for introduction into the coils. It is preferable to introduce cracked products containing products of the cracking of reduced crude into a common evaporator and to introduce cracked products free from products of cracking of reduced crude into a separate common evaporator. For example, cracked products from heaters 5| '54 and 51 containing the products of cracking of reduced crude may be introduced into evaporator 14 while such cracked products as are free of products of cracking of reduced crude are introduced into evaporator 18 by suitable manipulation of the valves as described above.

.If desired, however, one evaporator may be used for the cracked products from all three of heaters 5|, 54 and 51, and where each of these 757 heaters is utilized for the cracking of reduced crude by introduction as described above theuse of a single evaporator is sufficient.

It is advantageous, however, to provide a separate evaporatorior cracked products from those heaters into which a reduced crudehas not been introduced for cracking treatment since such cracked products will ordinarily contain naphtha of the higher anti-knock value whereas products of the cracking of reduced crude may contain substantial proportions of naphtha of lower anti-knock value, and it is advantageous from the standpoint of subsequent treatment and blending to have these two grades separated.

Evaporator 14 is operated to effect passage overhead of vapors including suitable recycle material and the production of fuel oil which collects in the bottom thereof for withdrawal through line 85 provided with control valve 86. Suitable bafiling may be arranged in the top portion of evaporator 14 along with refluxing facilities not shown to effect removal of entrained matter from the vapors and permit the production of a clean cycle stock in fractionator 90. Evaporator 14 may, for example, be maintained at a pressure of 50 to 300 pounds per square inch and with a bottom temperature of 750 to 850 F.

The vapors from evaporator 14 are Withdrawn therefrom through line 88 and are introduced into fractionator 90. Fractionator 90 is provided with cooling means 92 in the upper portion thereof, and it is operated to efiect condensation and collection in the bottom thereof of a suitable cycle stock and passage overhead of a gasolinecontaining distillate which is withdrawn through line 93. For example, fractionator 90 may be operated at substantially the same pressure as evaporator 14 with a bottom temperature of 550 to 650 F. and a top temperature of 350 to 425 F.

The trap-out tray is provided at a suitable place in iractionator 90 to efiect collection of a heavy naphtha condensate which may be withdrawn therefrom through line 98 provided with a control valve 91 for introduction into line 49 and passage to reforming heater 5|. Suitable gas-and-liquid contact means are provided in fractionator 90 to efiect the condensation and evaporation incidental to fractionation.

The cycle condensate collected in. the bottom of. fractionator 90 is withdrawn therefrom through line 55 provided with control valve 98 and introduced into the coil of heater 51 by means ofpump 56, as described above.

Evaporator 18 may be operated under conditions comparable to those in evaporator 14 to cheat the passage overhead of. vapors including suitable recycle constituents. Suitable bafliing may be provided in the upper portion thereof along with refluxing facilities to effect removal of entrained material from the vapors. Liquids separated are removed through line 99 provided with valve I03.

Uncondensed vapors from evaporator 18 pass overhead through line I00 and are introduced into fractionator I02. Fractionator I02 is provided with cooling means I04 in the upper portion thereof and is operated under conditions of temperature and pressure to effect condensation of a suitable cycle stock which collects in the bottom of fractionator I02 and passage overhead of a gasoline-containing distillate which is withdrawn through line I05. For example, iractionator I02 may be operated at approximately the same pressure as evaporator 18 with a bottom temperature of 550 to 650 F. and a top temperature of 350 to 450 F. Fractionator I02 is provided with suitable gas-and-liquid contact means to effect the desired fractionation.

The cycle stock is withdrawn from the lower portion of fractionator I02 through line I01 provided with control valve I08 which line connects with line 55 whereby the cycle stock from fractionators and I02 may be combined for passage to the inlet of the coil of heater 51.

The vapors and accompanying normally gaseous constituents passing overhead through lines 41, 93 and I05 are passed through condensers I09, H0 and III, respectively, wherein they are cooled to effect condensation of gasoline constit-' uents. The resulting mixtures of liquids and gases are passed through lines H2, H3 and H4, respectively, to separators H5, H6 and H1 wherein separation of the gases and liquids occurs. The liquids may be withdrawn from separators '5, II 0 and H1 through lines H8, H9 and I20, respective1y, provided with control valves I2I, I22 and I23 for separate treatment; or drawoif lines I24, .I25 and I28 provided with control valves I21, I28 and I29 and connecting with common lines, I30 may be. provided to effect blending of the various gasolines in any desired proportion in line I30 through suitable manipulation of valves I21, I28 and I29.

' Uncondensed gases separated in separators H5, H6 and H1 are withdrawn therefrom through lines I3 I,. I32 and I33, respectively, which are provided with control valves I34, I35 and I36 and connect with common line I31. Line I31 connects with a fractionator I38 after passage through a compressor I45 and any desired heat exchange such as described below. In fractionator I38 conditions of temperature and pres- .sure areimaintained to effect separation of convertible normally gaseous hydrocarbons, desired for passage through line 64 for introduction into heaters BI, 54 and'51 as described above, as a condensate which collects in the bottom of fractionator -I3 8. This condensate is withdrawn through line 64 by means of pump. I39 and passed to heaters 5|, 54 and 51 as desired after being preheated if desired through heat exchange with the gases in line I31 in heat exchanger I40, with the vapors passing through line I05 in heat exchanger MI, and with the vapors passing through line 93 in heat exchanger I42. Reboiling means l43 may be provided in the bottom of tower I38 to strip from the condensate therein any undesired light constituents. Cooling means I44 may be provided in the upper portion of fractionator I38 to effect the desired fractionation. For example, fractionator I38 may be operated at a pressure of 300 to 350 pounds per square inch with a bottom temperature of to F. and a top temperature of 30 F. It may, under some circumstances, be advantageous to .fractionate the cracked gasoline issuing from line I30 to free it from all hydrocarbons below the C series and to return the lighter hydrocarbons so produced to fractionator I38 along with the gas from line I31.

Preferably, the condensate collected in the bottom of fractionator I38 predominates in the C3 and C4 hydrocarbons which are most susceptible to conversion to gasoline constituents in heaters 5|, 54 and 51. The uncondensed gases are withdrawn through line I45 provided with control valve I41. :The relatively low temperature of 5 P pl h line I40, especially after expansion through va ve I may be utilized in any suitable manner in the operation of fractionator' I38.

It is to be understood, of course, that the gases passing through line l3! may be used as such for introduction into the coils of heaters :5], 54 and 57 through line 64. For example, line I50 connecting line I31 and line 64 may be provided to divert all or a portion of the gases around the fractionators I38 and pass them directly to the heaters. Valves l5! and I52 may be provided in lines 158 and I31, respectively, to effect the desired distribution of gases.

While the coils of heaters 5|, 54 and 51 are illustrated as being housed in separate structures it isto be understood, of course, that they may constitute separate coils each located in a furnace structure which may also house one or more other coils. For example, the coils of heaters 51, 54 and 51 may be arranged in a single heater in the parts thereof wherein they are subjected to the desired applications of heat. Furthermore, the various portions of each coil may be arranged in different parts of the furnace whereby each portion receives the desired application of heat depending upon its function as a heating or reaction zone or both. It is also to be understood that although the figures herein show all conversion and reactions to be effected in the coils of the heaters separate reaction chambers may alternately be employed for maintaining the hydrocarbons under the proper conditions for the necessary length of time.

It is to be understood also that the relative proportions of the various intermediate products returned to the system may vary within wide limits, and any portions undesired for further treatment in the system may be withdrawn therefrom by separate means which are omitted from the drawing for purposes of simplification. Furthermore, additional materials similar to the intermediate products produced in the system may be introduced for use in combination with such intermediate products to remedy any deficiency thereof. It is to be further understood that the materials charged to the heaters may be preheated to any desired temperature by any necessary means not shown and that the cracked products therefrom may be cooled prior to evaporation by any suitable means such as heat exchange with cooler products produced elsewhere in the system. 1

The present invention thus provides a suitable means for the treatment of a plurality of hydrocarbons of differing boiling ranges by relatively simple means and under conditions of maximum efficiency to efiect maximum conversion thereof into motor fuel of high anti-knock value. a The more specific advantages of the present invention are clearly apparent from the foregoing description.

It is to be understood, however, that the descriptions in reference to specific apparatus are merely for purposes of illustration, the invention of temperature and pressure to effect substantial conversion thereof to lower-boiling products including motor-fuel constituents of high antiknock value, fractionating the resultant conversion products in a second fractionating zone to separate therefrom motor-fuel condensate, a gasoil condensate above the motor-fuel boiling range and normally gaseous hydrocarbons predominating in hydrocarbons heavier than ethane, separately subjecting gas-oil condensate thus obtained to cracking conditions of temperature and pressurein the first portion of a separate cracking zone to effect conversion thereof to lighter products including motor-fuel constituents, merging with hot products of said last-mentioned cracking operation higher-boiling hydrocarbon oil from said crude oil fractionation and normally gaseous hydrocarbons thus obtained, subjecting products of said merging operation in the second portion of said separate cracking zone to cracking conditions of temperature and pressure to efiect conversion thereof to motor-fuel constituents of high anti-knock value and subjecting the resulting products of conversion to fractionation, separately from said fractionation of the crude oil, to recover a motor-fuel product.

2. The method of treating hydrocarbons to produce therefrom motor fuel of high anti-knock value which comprises distilling crude oil to separate it into vapors and residue and fractionating the separated vapors in a fractionating zone to produce a straight run gas oil condensate, subjecting said straight run gas oil condensate to cracking conditions of temperature and pressure in a single pass cracking zone to effect conversion into lower boiling products comprising motor fuel constituents of high anti-knock value, separating the resultant cracked products into residue and vapors and gases, passing the separated vapors to a second fractionating zone wherein they are fractionated to separate therefrom motor fuel distillate, reflux condensate above the motor fuel boiling range, and normally gaseous hydrocarbons predominating in hydrocarbons higher boiling than C2 hydrocarbons, passing said reflux condensate to the first portion of a separate recycling cracking zone wherein the condensate is subjected to cracking conditions .of temperature and pressure .to effect conversion into lighter products including motor fuel constituents, merging with the resultant cracked products of said last-mentioned cracking operation crude residue obtained in the distillation of the crude oil and normally gaseous being capable of other embodiments which may be beyond the physical limitations of the appa ratus illustrated.

I claim:. 1. The method of treating hydrocarbons to produce therefrom motor fuel of high anti-knock separately subjecting said virgin gas oil in a single pass cracking zone to cracking conditions subjecting the merged products in a second portionlof said separate recycling cracking zone to cracking conditions .of temperature and pressure to effect conversion into motor fuel constituents of high anti-knock value and subjecting the resulting products of conversion to fractionation separately from said distilling and fractionating of the crude oil to recover a motor fuel product.

- 3. The method of treating hydrocarbons to produce therefrom motor fuel of high anti-knock value which comprises distilling crude oil to separate it into vapors and residue and fractionating the separated vapors in a fractionating zone to produce a straight run gas oil condensate, subjecting said straight run condensate to cracking conditions of temperature and pressure to effect conversion into lower boiling products comprising motor fuel constituents of high antiknock value, separating the resultant cracked products into residue and vapors and gases, fractionating the separated vapors and gases in a second fractionating zone to separate therefrom motor fuel distillate, reflux condensate above the motor fuel boiling range, and normally gaseous hydrocarbons predominating in hydrocarbons higher boiling than C2 hydrocarbons, passing said reflux condensate to a separate cracking zone comprising an elongated heating zone of restricted cross section wherein the oil is heated to cracking temperature under superatmospheric pressure and subjected to conversion, introducing crude residue obtained in the distillation of the crude oil into an intermediate point in said elongated heating zone to thereby subject the crude residues to conversion, simultaneously infrom said distilling and fractionating of the crude oil, to recover a motor fuel product.

GEORGE ARMISTEAD, JR. 

